Hot water space heater

ABSTRACT

A hot water forced air circulation heater is disclosed and is particularly adapted for use with one or more electric immersion heating elements. The space heater includes a casing having an upper heat exhanger section and a lower blower section. A convector structure is mounted within the heat exchange section and arranged for the output of the blower to flow therearound. The convector is of serpentine or double serpentine construction and its ends are coupled to a reservoir for water or other heat exchange medium heated by one or more of the heating elements mounted in the reservoir. The convector-conduit and convecting fins associated therewith are sized such that heat exchange water is returned to the reservoir with a substantial quantity of sensible heat to minimize thermal cycling of the heating element or elements and to increase the effective heat transfer area of the convector. The blower output is blown longitudinally of the convector or upwardly through the heat exchange section to maximize contact between the air and the convector. In one arrangement the circulating water reservoir is mounted near the base of the convector on a projecting portion of the casing and is connected through a riser conduit to the inlet at the top of the convector. The upper portion of the convector can be arranged to overhang the reservoir to facilitate connection of the convector to the riser conduit and to give direction to hot air issuing from the space heater.

United States Patent 72] Inventors Emanuel Ferraro;

Oliver Ferraro; James Ferraro; Paul Ferraro, 916 Baldwin St.,Pittsburgh, Pa. 15234 [21] Appl. No. 669,434 [22] Filed Sept. 21,1967[45] Patented Mar. 2, 1971 [54] HOT WATER SPACE HEATER 13 Claims, 5Drawing Figs.

[52] US. Cl 219/365, 126/101, 219/341, 219/370, 237/16 [51] Int. Cl H05b3/00 [50] Field ofSearch 219/341, 365, 366-368, 369, 370; 237/16-18;126/101 [56] References Cited UNITED STATES PATENTS 2,290,402 7/1942Witte 219/365X 2,491,849 12/1949 Broome... 219/365 2,518,982 8/1950Edwards. 219/341X 2,553,508 5/1951 White 219/365 FOREIGN PATENTS1,118,759 3/1956 France 237/16 Primary Examiner-A. BartisAttorney-Buell, Blenko & Ziesenheim ABSTRACT: A hot water forced aircirculation heater is disclosed and is particularly adapted for use withone or more electric immersion heating elements. The space heaterincludes a casing having an upper heat exhanger section and a lowerblower section. A convector structure is mounted within the heatexchange section and arranged for the output of the blower to flowtherearound. The convector is of serpentine or double serpentineconstruction and its ends are coupled to a reservoir for water or otherheat exchange medium heated by one or more of the heating elementsmounted in the reservoir. The convector-conduit and convecting finsassociated therewith are sized such that heat exchange water is returnedto the reservoir with a substantial quantity of sensible heat tominimize thermal cycling of the heating element or elements and toincrease the effective heat transfer area of the convector. The bloweroutput is blown longitudinally of the convector or upwardly through theheat exchange section to maximize contact between the air and theconvector. In one arrangement the circulating water reservoir is mountednear the base of the convector on a projecting portion of the casing andis connected through a riser conduit to the inlet at the top of theconvector. The upper portion of the convector can be arranged tooverhang the reservoir to facilitate connection of the convector to theriser conduit and to give direction to hot air issuing from the spaceheater.

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Janna; Fer/111 0 Jl'acd IZ'n/wra THEY)? HWIOR/Vi' 1 9 PATENTED MAR 2197!SHEET 2 [1F 2 1 nor WATER SPACE HEATER DESCRIPTION OF THE INVENTION Thepresent invention relates to hot water space heaters suitable forheating dwelling and office rooms and larger areas. More particularlythe invention relates to a heater of the character described whichexhibits a marked increase in efficiency in comparison to prior spaceheaters. The space heater of the invention is especially designed foruse with an electric heat source, although other heat sources obviouslycan be used.

Previously there has been no effective means for converting electricalenergy into heat with an efficiency in comparison to that of heatingsystems in which fossil fuels are directly combusted. The advantages ofthe economic use of electric energy for heating purposes are obvious.The dust, dirt, soot, ashes, combustion gases associated with burningfuels are largely eliminated in a properly constructed electricalheating system. The flue connections necessary with combustion-typeheaters are also obviated;

Previously proposed electric space heaters employing water as a heattransfer medium have been ineffective largely because of their lack ofacceptable conversion efficiencie's. For example, in a prior electrichot water space heater, as proposed in US. Pat. No. 2, 197,298 to Cobbthe air was force-circulated through the heat exchanger in a directiontransverse to the flow of heat-exchange water therethrough. As a result,the air was subjected to differing temperatures existing across the heatexchange area, with the result that some of the air was heatedsufficiently while-other portions were barely heated at all. The Cobbheat exchanger was arranged such that the flow of water therethrough bygravity was largely ineffective. In the Cobb heater an attempt was madeto remove as much heat as possible from the heat-exchange water bycirculating the water through heat exchanging means having parallel,extremely tortuous paths with the result that the return water was toocold for efficient reheating. Not only was the heating element subjectedto severe temperature cycling but also the element could not operate atits most effective level.

Other previously proposed electric spaced heaters have suffered fromsimilar defects and need not to be specifically described.

We overcome these difficulties of the prior art by providing an electrichot water spacer which utilizes a convector rather than a heat exchangerfor more effective water-to-air heat transfer. Our space heater isprovided with a continuous full flow of water through the convectorrather than through headers coupled to branched portions ofa heatexchanger. As a result we advantageously utilize gravitational forces incirculating the water. This arrangement provides our space hot waterheater with a quick recovery system and minimizes thermal cycling. Wealso provide a blower arrangement in which the air is propelledgenerally in the direction opposite to that of the flow of water throughthe convector so that the air is more gradually but more effectivelywarmed by first coming into contact with those portions of the convectorcontaining the cooler portions of the heat-exchange water so that theheating air exits from the heater directly from the hottest portion ofthe convector. This heating andcooling arrangement of the air and waternot only considerably increases the efficiency of heat transfer but alsopermits all of the heated air to exit at substantially the sametemperature.

In addition to the aforementioned novel features of our invention, wehave also discovered that the efficiency of our space heater can beincreased still further to a marked extent by arranging the water volumeof the convector to be substan- 1 and a heat exchange section, aheat-exchange water reservoir mounted on said casing, heat-producingmeans mounted in heat transfer relation to said reservoir, a convectormounted in said heat exchange section and substantially coexistingtherewith for conveying heat-exchange water generally downwardlythereof, an upper inlet port of said convector coupled to a hot wateroutlet of said reservoir, a lower outlet port of said convector coupledto a return water inlet of said reservoir, said casing having a warm airoutlet in the upper portion thereof communicating with said heatexchange section and a cold air return in the lower portion thereofcommunicating with said base section, and a blower mounted in saidcasing base section having its inlet communicating with said returnopening and having its outlet communicating with said heat exchangesection so that blower output air flows upwardly thru said heat exchangesection and concurrently to the general flow direction of saidheat-exchange water.

In certain advantageous forms of our hot water heater said base sectionprojects outwardly of said heat exchange section, and said reservoir ismounted on the projecting portion of said base section, the outlet ofsaid reservoir being coupled to the inlet of said convector through anexternal standpipe.

In cooperation therewith an upper air outlet portion of said heatexchange section overhangs said base extension and said reservoir, andthe junction betweensaid standpipe and said convector inlet is mountedwithin said overhanging portion.

For maximum efficiency of our space heater the size of said convectorconduit and a number of cooling fins associated therewith are selectedsuch that said water is returned to said reservoir with a substantialamount of sensible heat remaining therein; or the volume of watercontainable in said reservoir is between 40 and 50 percent of the totalamount of water containable in said convector and in said reservoir; orboth.

During the foregoing discussion, various objects, features andadvantages of the invention have been alluded to. These and otherobjects, features and advantages together with structural detailsthereof will be elaborated upon during the forthcoming description ofpresently preferred embodiments of our invention and presently preferredmethods of practicing the same.

In the accompanying drawings we have shown presently preferredembodiments of the invention and have illustrated certain presentlypreferred methods of practicing the same, wherein:

FIG. 1 is a side elevational view of one form of our novel hot waterspace heater, with parts being removed to show the invention moreclearly;

FIG. 2 is a vertically sectioned view of the apparatus shown in FIG. 1and taken along reference line IIII thereof;

FIG. 3 is a front elevational view of the apparatus shown in thepreceding FIGS. and exemplarily incorporating a schematic electricaloperating circuit;

FIG. 4 is a left side elevational view of another form of hot waterspace heater arranged in accordance with our invention with partsremoved and other parts in section to illustrate the invention moreclearly; and

FIG. 5 is a rear elevational view, with parts removed, of the apparatusas shown in FIG. 4.

Referring now more particularly to FIGS. 1-3 of the drawings, anexemplary form of our hot water space heater 10 shown therein comprisesa'casing 12 including a heat transfer section 14 and a base of airintake section 16. As better shown in FIGS. 2 and 3 a blower 18 ismounted within the air intake section 16, and has its outlet coupled toa baffle structure 20 to the lower end of the heat transfer section 14as better shown in FIG. I. The blower 18 is driven by motor 22, and itsintake communicates thru to the interior of base section 16 and returnor cold air grill 24 (FIG. 3) with the ambient. If desired, a suitabledust filter (not shown) or the like can be mounted between the blowerintake and the cold air return grill 24. The blower output is directedgenerally countercurrently of the heat-exchange water flow, as explainedbelow, and upwardly through the heat exchange housing section 14 asdenoted by flow arrow 26 and exits therefrom through the upper or warmair register 28 (FIG. 3).

As mentioned, the heat-exchange water medium is arranged to flow ingenerally the opposite direction to the blower output, i.e., downwardlythrough convector arrangement denoted generally by reference character30.In furtherance of this purpose water is heated in reservoir tank 32by suitable heatproducing means, for example, electric immersion heatingelement 34, with the heated water rising by convection through standpipe36, as denoted by flow arrow 38.

From a point near the upper end of the standpipe 36 the heated waterflows into the uppermost run 40a of the convector 30. Thence the heatedwater flows generally downwardly of the heat transfer section 14, alonga serpentine path as defined by conduit 42. In this example, eachhorizontal run of the conduit 42 is provided with a relatively largenumber of convecting fins 44 to facilitate transfer of the heat from theconvector 30 to the upwardly flowing air through the heat transferhousing 14. The lowermost run 40b of the serpentine conduit 42 iscoupled through connecting conduit 46 to the water reservoir 32. Formaximum efficiency the convector 42- 44 desirably is coextensive withthe heat exchange casing I section 14.

the upper or heat transfer housing 14 in order to minimize the number ofexposed conduits. Conduit 39 joins standpipe 36 below its junction withconvector 30 so as not to interfere with the escape of air from theconvector 30 during filling. As the system is filled with water thedisplaced air escapes through vent 37. The system also is provided witha relief valve 41 desirably mounted on the upper side of the reservoir32.

The size of the serpentine conduit 42 and the number and size ofconvecting fins 44 are selected such that the water medium is returnedthrough conduit 46 to the reservoir 32 with a substantial amount of itssensible heat remaining, in contrast to previous heating systems whichattempted to wring all sensible heat out of the heat-exchange water bymeans of complicated heat exchange means. Our unique convector 30 iscapable 'of transferring significant quantities of heat from the waterto the upflowing air even in the lowermost region of the convector 30.Thus, by delivering the water from conduit 46 to reservoir 32 at arelatively warm temperature, we attain a correspondingly greater andmore effective heat transfer area in the convector 30.

In order to provide a compact space heater we mount the reservoir tank32 upon ledge 48 formed by the outwardly projecting portion of the basesection 16. In this arrangement the standpipe 36 preferably is extendedacross the shorter, open distance from the top of the reservoir tank 36to the upper most run 40a of the serpentine conduit 42. To conserve heatand to prevent injury to personnel the standpipe 36 can be lagged with asuitable and known pipe insulation 50. Similar insulation 52 can beplaced from reservoir chamber 32 if desired. Likewise the exposedportion of the conduit 46 can be lagged (not shown) if desired.

We have also found that the quantity of water contained in the convectorconduit 42 must bear a definite relationship to i the quantity of watercontained in the reservoir 32, for maximum efficiency. Thus, we havefound that when the volume of water in the convector 30 is about equalto the volume of water in reservoir 32, the electric hot water spaceheater operates at maximum efficiency. A significant imbalance in thisvolumetric relationship introduces a marked decrease in heat transferefficiency. Thus, if the volume of water in reservoir 32 is less than 40percent or greater than 50 percent of the total water volume containedin reservoir 32 and convector 42, a significant impairment in operatingefficiency results.

Referring now to FIG. 3 of the drawings a typical control system for ournovel. space heater is shown therein. A junction box 54 in this exampleis connected in the usual manner to a source (not shown) of linevoltage. .The fan motor 22 and heating element 34 are coupled inparallel to the junction box. An overload or upper limit switch 56 iscoupled in the ground circuit of the heating element while a roomthermostat 58 and fan control 60 are connected in series in the supplycircuit of fan motor 22.

Referring now to FIGS. 4 and 5 of the drawings another form of our novelhot water space heater is illustrated. Space heater 62 is arranged inthis example for 'a-substantially larger output than that shown in thepreceding FIGS. In this arrangement the heat transfer housing section14' is substantially increased in horizontal cross-sectional area inorder to accommodate a convector 30 having a conduit 42' of doubleserpentine configuration as shown. A correspondingly larger waterreservoir 32 is employed and in this example is entirely included withinthe furnace housing 12', as is standpipe 36.

In the space heater 62 the principle of operation are generally the sameas that of the heater 10 shown in FIGS. 1- -3, with the blower outputbeing directed upwardly as denoted by flow arrow 26 and the heattransfer medium or heat-exchange water flowing generally downwardlythrough convector 30 as denoted by arrow 64. Desirably the water volumeof reservoir 32 is about equal to the water contained in conduit 42 ofthe convector 30.

In the arrangement of FIGS. 4 and 5 however, the housing 12' includes anoutlet plenum chamber 66 in the vertical sides of which one or more warmair registers 28 can be mounted. It also is contemplated thatconventional heating ductwork (not shown) can be coupled to the plenumchamber 66 and that a cold air return duct (not shown) coupled tohousing base section 16. By the same token the return grill 24 and warmair register 28 of FIGS. 1-3 can be omitted, and the openings thereforcoupled to conventional hot air and return ducts (not shown).

From the foregoing it will be apparent that we have disclosed novel andefficient forms of hot water space heaters. While we have shown anddescribed certain presently preferred embodiments of the invention andhave illustrated presently preferred methods of practicing the same itis to be distinctly understood that the invention is not limited theretobut may be otherwise variously embodied and practiced within the scopeof the following claims.

We claim:

1. A hot water heater including a casing having a base section and aheat exchange section, a heat-exchange water reservoir mounted on saidcasing, heat-producing means mounted in heat transfer relation to saidreservoir, a convector mounted in said heat exchange section andsubstantially coextending therewith for conveying heat-exchange watergenerally downwardly thereof, an upper inlet port of said convectorcoupled to a hot water outlet of said reservoir, a lower outlet port ofsaid convector coupled to a return water inlet of said reservoir, saidcasing having a warm air outlet in the upper portion thereofcommunicating with said heat exchange section and a cold air return inthe lower portion thereof communicating with said base section, and ablower mounted in said casing base section having its inletcommunicating with said return opening and having its outletcommunicating with said heat exchange section so that blower output airflows upwardly through said heat exchange section and countercurrentlyto the general flow direction of said heat-exchange water through saidheat exchange section, said reservoir being mounted on said casingadjacent the lower portion of said convector and having its hot wateroutlet coupled through a standpipe to the upper inlet port of saidconvector, said standpipe extending upwardly from the upper side of saidreservoir, and said convector coextending substantially with thecombined length of said reservoir and standpipe.

2. The combination according to claim I wherein the size of saidconvector conduit and a number of cooling fins as sociated therewith areselected such that said water is returned to said reservoir with asubstantial amount of sensible heat remaining therein.

3. The combination according to claim 2 wherein the volume of watercontainable in said reservoir is between 40 and 50 percent of the totalamount of water containable in said convector and in said reservoir.

4. The combination according to claim 1 wherein said convector includesa serpentine conduit.

5. The combination according to claim 1 wherein said convector includesa double serpentine conduit.

6. A hot water heater including a casing having a base section and aheat exchange section, a heat-exchange water reservoir mounted on saidcasing, heat-producing means mounted in heat transfer relation to saidreservoir, a convector mounted in said heat exchange section andsubstantially coextending therewith for conveying heat-exchange watergenerally downwardly thereof, an upper inlet port of said convectorcoupled to a hot water outlet of said reservoir, a lower outlet port ofsaid convector coupled to a return water inlet of said reservoir, saidcasing havinga warm air outlet in the upper portion thereofcommunicating with said heat exchange section and a cold air return inthe lower portion thereof communicating with said base section, and ablower mounted in said casing base section having its inletcommunicating with said return opening and having itsoutletcommunicating with said heat exchange section so that blower output airflows upwardly through said heat exchange section and countercurrentlyto the general flow direction of said heat-exchange water, said basesection projecting outwardly of said heat exchange section, and saidreservoir being mounted on the projecting portion of said base section,the outlet of said reservoir being coupled to the inlet of saidconvector through an external standpipe.

7. The combination according to claim 6 wherein an upper air outletportion of said heat exchange section overhangs said base extension andsaid reservoir, and the junction between said standpipe and saidconvector inlet is mounted within said overhanging portion.

8. A hot water heater including a casing having a base section and aheat exchange section, a heat-exchange water reservoir mounted on saidcasing, heat-producing means mounted in heat transfer relation to saidreservoir, a convector mounted in said heat exchange section andsubstantially coextending therewith for conveying heat-exchange watergenerally downwardly thereof, an upper inlet port of said convectorcoupled to a hot water outlet of said reservoir, a lower outlet port ofsaid convector coupled to a return water inlet of said reservoir, saidcasing having a warm air outlet in the upper portion thereofcommunicating with said heat exchange section and a cold air return inthe lower portion thereof communicating with said base section, and ablower mounted in said casing base section having its inletcommunicating with said return opening and having its outletcommunicating with said heat exchange section so that blower output airflows upwardly through said heat exchange section and countercurrentlyto the general flow direction of said heat-exchange water, saidreservoir being mounted on said casing adjacent the lower output portionof said convector and being coupled through a standpipe to the upperinlet portions of said convector, the upper end of said standpipeprojecting above its junction with said convector inlet and through theadjacent portion of said casing and tenninating in an air vent for saidliquid system.

9. The combination according to claim 8 wherein a capped fill pipe ismounted in said casing with its capped end projecting through the upperend thereof and the lower end communicating with said standpipe at apoint below the junction of said standpipe and said convector inlet soas not to interfere with the escape of air from said convector.

10. The combination according to claim 9 wherein a portion of said heatexchange section overhangs said base section, said fill pipe and itsjunction with said standpipe are enclosed within said overhanging heatexchange portion.

11. A hot water heater includlng a casing having a base section and aheat exchange section, a heat-exchange water reservoir mounted on saidcasing, heat-producing means mounted in heat transfer relation to saidreservoir, a convector mounted in said heat exchange section andsubstantially coextending therewith for conveying heat-exchange watergenerally downwardly thereof, said reservoir being mounted on saidcasing adjacent the lower output portion of said convector and beingcoupled through a standpipe to the upper inlet portion of saidconvector, an upper inlet port of said convector coupled to a hot wateroutlet of said reservoir, a lower outlet port of said convector coupledto a return water inlet of said reservoir, said casing having a warm airoutlet in the upper portion thereof communicating-with said heatexchange section and a cold air return in the lower portion thereofcommunicating with said base section, said reservoir being mounted onsaid casing adjacent the lower portion of said convector and having itshot water outlet coupled through a standpipe to the upper inlet port ofsaid convector, said-standpipe extending upwardly from the upper side ofsaid reservoir, and said convector coextending substantially with thecombined length of said reservoir and standpipe, the volume of watercontainable in said reservoir being about equal to the volume of watercontainable in said convector.

12. A hot water heater including a casing having a base section and aheat exchange section, a heat-exchange water reservoir mounted on saidcasing, heat-producing means mounted in heat transfer relation to saidreservoir, a convector mounted in said heat exchange section andsubstantially coextending therewith for conveying heat-exchange watergenerally downwardly thereof, an upper inlet port of said convectorcoupled to a hot water outlet of said reservoir, a lower outlet port ofsaid convector coupled to a return water inlet of said reservoir, saidcasing having a warm air outlet in the upper portion thereofcommunicating with said heat exchange section and a cold air return inthe lower portion thereof communicating with said base section, thevolume of water containable in said reservoir is about equal to thevolume of water containable in said convector.

13. The combination according'to claim 9 wherein a blower is mounted insaid casing base sectionand has its inlet communicating with said returnopening. and its outlet communicating with said heat exchange section sothat blower output air flows upwardly through said heat exchange sectionand countercurrently to the general flow direction of said heatexchangewater through said heat exchange section.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N05 567 905Dated March 2 1971 Inventor) Emanuel Ferraro et a1 It is certified thaterror appears in the above-identified paten' and that said LettersPatent are hereby corrected as shown below:

In the Abstract, line 4, "exhanger" should read exchanger line 22, after"the", third occurrence, ins heat exchange compartment and the adjacentportion Signed and sealed this 20th day of July 1971.

(SEAL) Attest:

EDWARD M. FLETCI-IER,JR. WILLIAM E. SCHUYLER, J1

Attesting Officer Commissioner of Patent:

1. A hot water heater including a casing having a base section and aheat exchange section, a heat-exchange water reservoir mounted on saidcasing, heat-producing means mounted in heat transfer relation to saidreservoir, a convector mounted in said heat exchange section andsubstantially coextending therewith for conveying heat-exchange watergenerally downwardly thereof, an upper inlet port of said convectorcoupled to a hot water outlet of said reservoir, a lower outlet port ofsaid convector coupled to a return water inlet of said reservoir, saidcasing having a warm air outlet in the upper portion thereofcommunicating with said heat exchange section and a cold air return inthe lower portion thereof communicating with said base section, and ablower mounted in said casing base section having its inletcommunicating with said return opening and having its outletcommunicating with said heat exchange section so that blower output airflows upwardly through said heat exchange section and countercurrentlyto the general flow direction of said heatexchange water through saidheat exchange section, said reservoir being mounted on said casingadjacent the lower portion of said convector and having its hot wateroutlet coupled through a standpipe to the upper inlet port of saidconvector, said standpipe extending upwardly from the upper side of saidreservoir, and said convector coextending substantially with thecombined length of said reservoir and standpipe.
 2. The combinationaccording to claim 1 wherein the size of said convector conduit and anumber of cooling fins associated therewith are selected such that saidwater is returned to said reservoir with a substantial amount ofsensible heat remaining therein.
 3. The combination according to claim 2wherein the volume of water containable in said reservoir is between 40and 50 percent of the total amount of water containable in saidconvector and in said reservoir.
 4. The combination according to claim 1wherein said convector includes a serpentine conduit.
 5. The combinationaccording to claim 1 wherein said convector includes a double serpentineconduit.
 6. A hot water heater including a casing having a base sectionand a heat exchange section, a heat-exchange water reservoir mounted onsaid casing, heat-producing means mounted in heat transfer relation tosaid reservoir, a convector mounted in said heat exchange section andsubstantially coextending therewith for conveying heat-exchange watergenerally downwardly thereof, an upper inlet port of saiD convectorcoupled to a hot water outlet of said reservoir, a lower outlet port ofsaid convector coupled to a return water inlet of said reservoir, saidcasing having a warm air outlet in the upper portion thereofcommunicating with said heat exchange section and a cold air return inthe lower portion thereof communicating with said base section, and ablower mounted in said casing base section having its inletcommunicating with said return opening and having its outletcommunicating with said heat exchange section so that blower output airflows upwardly through said heat exchange section and countercurrentlyto the general flow direction of said heat-exchange water, said basesection projecting outwardly of said heat exchange section, and saidreservoir being mounted on the projecting portion of said base section,the outlet of said reservoir being coupled to the inlet of saidconvector through an external standpipe.
 7. The combination according toclaim 6 wherein an upper air outlet portion of said heat exchangesection overhangs said base extension and said reservoir, and thejunction between said standpipe and said convector inlet is mountedwithin said overhanging portion.
 8. A hot water heater including acasing having a base section and a heat exchange section, aheat-exchange water reservoir mounted on said casing, heat-producingmeans mounted in heat transfer relation to said reservoir, a convectormounted in said heat exchange section and substantially coextendingtherewith for conveying heat-exchange water generally downwardlythereof, an upper inlet port of said convector coupled to a hot wateroutlet of said reservoir, a lower outlet port of said convector coupledto a return water inlet of said reservoir, said casing having a warm airoutlet in the upper portion thereof communicating with said heatexchange section and a cold air return in the lower portion thereofcommunicating with said base section, and a blower mounted in saidcasing base section having its inlet communicating with said returnopening and having its outlet communicating with said heat exchangesection so that blower output air flows upwardly through said heatexchange section and countercurrently to the general flow direction ofsaid heat-exchange water, said reservoir being mounted on said casingadjacent the lower output portion of said convector and being coupledthrough a standpipe to the upper inlet portions of said convector, theupper end of said standpipe projecting above its junction with saidconvector inlet and through the adjacent portion of said casing andterminating in an air vent for said liquid system.
 9. The combinationaccording to claim 8 wherein a capped fill pipe is mounted in saidcasing with its capped end projecting through the upper end thereof andthe lower end communicating with said standpipe at a point below thejunction of said standpipe and said convector inlet so as not tointerfere with the escape of air from said convector.
 10. Thecombination according to claim 9 wherein a portion of said heat exchangesection overhangs said base section, said fill pipe and its junctionwith said standpipe are enclosed within said overhanging heat exchangeportion.
 11. A hot water heater including a casing having a base sectionand a heat exchange section, a heat-exchange water reservoir mounted onsaid casing, heat-producing means mounted in heat transfer relation tosaid reservoir, a convector mounted in said heat exchange section andsubstantially coextending therewith for conveying heat-exchange watergenerally downwardly thereof, said reservoir being mounted on saidcasing adjacent the lower output portion of said convector and beingcoupled through a standpipe to the upper inlet portion of saidconvector, an upper inlet port of said convector coupled to a hot wateroutlet of said reservoir, a lower outlet port of said convector coupledto a return water inlet of said reservoir, said casing having a warm airoutlet in the upper portion thereof communicatiNg with said heatexchange section and a cold air return in the lower portion thereofcommunicating with said base section, said reservoir being mounted onsaid casing adjacent the lower portion of said convector and having itshot water outlet coupled through a standpipe to the upper inlet port ofsaid convector, said standpipe extending upwardly from the upper side ofsaid reservoir, and said convector coextending substantially with thecombined length of said reservoir and standpipe, the volume of watercontainable in said reservoir being about equal to the volume of watercontainable in said convector.
 12. A hot water heater including a casinghaving a base section and a heat exchange section, a heat-exchange waterreservoir mounted on said casing, heat-producing means mounted in heattransfer relation to said reservoir, a convector mounted in said heatexchange section and substantially coextending therewith for conveyingheat-exchange water generally downwardly thereof, an upper inlet port ofsaid convector coupled to a hot water outlet of said reservoir, a loweroutlet port of said convector coupled to a return water inlet of saidreservoir, said casing having a warm air outlet in the upper portionthereof communicating with said heat exchange section and a cold airreturn in the lower portion thereof communicating with said basesection, the volume of water containable in said reservoir is aboutequal to the volume of water containable in said convector.
 13. Thecombination according to claim 9 wherein a blower is mounted in saidcasing base section and has its inlet communicating with said returnopening and its outlet communicating with said heat exchange section sothat blower output air flows upwardly through said heat exchange sectionand countercurrently to the general flow direction of said heat-exchangewater through said heat exchange section.